Ambipolar Photoresponsivity in an Ultrasensitive Photodetector Based on a WSe2/InSe Heterostructure by a Photogating Effect.

Ambipolar photoresponsivity mainly originates from intrinsic or interfacial defects. However, these defects are difficult to control and will prolong the response speed of the photodetector. Here, we demonstrate tunable ambipolar photoresponsivity in a photodetector built from vertical p-WSe2/n-InSe heterostructures with photogating effect, exhibiting ultrahigh photoresponsivity from -1.76 × 104 to 5.48 × 104 A/W. Moreover, the photodetector possesses broadband photodetection (365-965 nm), an ultrahigh specific detectivity (D*) of 5.8 × 1013 Jones, an external quantum efficiency of 1.86 × 107%, and a rapid response time of 20.8 ms. The WSe2/InSe vertical architecture has promising potential in developing high-performance nano-optoelectronics.